Conventionally, a hydraulic pressure control valve is employed, for example, in a body of an automatic transmission device of a vehicle to control a hydraulic pressure to be applied to components in the automatic transmission device. The automatic transmission device has a body having a tubular cavity to which a hydraulic pressure control valve is equipped. The tubular cavity has a supply port, an outlet port, and a drain port. The supply port is connected to a supply source of hydraulic fluid. The outlet port is connected to a hydraulic pressure chamber of the controlled object. The drain port is connected to a drain destination of hydraulic fluid.
The hydraulic pressure control valve includes a sleeve having various kinds of ports. The hydraulic pressure control valve is equipped to the cavity such that the ports of the sleeve communicate with the ports of the body. Within the sleeve, a spool is manipulated in the axial direction to change a communication state between a supply port and an outlet port and a communication state between the outlet port and a drain port thereby to control a hydraulic pressure in the controlled object.
The sleeve of a hydraulic pressure control valve has, for example, a first port, a second port, and a third port, which are configured to communicate with the supply port, the outlet port, and the drain port, respectively. The spool includes multiple lands, which are slidable along the inner circumferential periphery of the sleeve. The spool is accommodated in the sleeve thereby to form three hydraulic chambers for hydraulic fluid. The three hydraulic chambers are partitioned by the lands. The first to third ports open in the hydraulic chambers, respectively. The spool is manipulated and moved within the sleeve in the axial direction thereby to control the communication states among the hydraulic chambers. Specifically, the spool is moved to change the communication state between the supply port and the outlet port and the communication state between the outlet port and the drain port.
It is noted that, hydraulic fluid supplied from the supply source and hydraulic fluid drawn from the controlled object flows into the hydraulic chamber in the sleeve to apply a dynamic pressure on the spool. This dynamic pressure biases the spool in a direction, which is not along the axial direction of the spool in which the spool is supposed to move. Therefore, the dynamic pressure caused by the hydraulic fluid flowing into the hydraulic chamber biases the spool in the radial direction. Thus, the dynamic pressure causes a hydraulic lateral force to bias the spool onto the inner circumferential periphery of the sleeve. The hydraulic lateral force may cause fluctuation in an operating characteristic of the hydraulic pressure control valve.
In recent years, the hydraulic pressure control valve is employed for controlling a hydraulic pressure in a presently emerged controlled object, such as a continuously variable transmission device, which requires high-pressure control compared with conventional control objects. It is expected that a quantity of flow of hydraulic fluid, which flows through the hydraulic chamber, further increases. Therefore, it is conceivable that the hydraulic lateral force further increases to exert further remarkable influence of hydraulic lateral force on the operating characteristic of a hydraulic pressure control valve. In view of these backgrounds, it may be desirable to provide a configuration to enable reduction in influence of the hydraulic lateral force exerted on the operating characteristic of a hydraulic pressure control valve.
(Patent Document 1)
Publication of Unexamined Japanese Patent Application No. H10-289018